It does seem like a missed opportunity for valuable information. It is certainly something that might help to further inform the decisions we have to make. If other countries (the UK records this) can do it then it must be possible and of value.
Research about treatments and their effectiveness in preventing recurrence are based on limited numbers of people sampled in individual studies. Surely keeping track of what happens to general populations would give so much more information. I guess it comes down to money to fund the recording of such a large amount of information.